Low-threshold field emission from transparent p-type conducting CuAlO2 thin film prepared by dc sputtering

We have observed the low-macroscopic field (LMF) emission, at a relatively lower threshold, from a wide bandgap CuAlO2 thin film having p-type conductivity deposited on glass substrate. The emission properties have been studied for different anodesample spacing. The range of the threshold field is calculated and we have tried to explain the emission mechanism therefrom. The threshold field has been found to be as low as 0.9 V/mm. This unusually low threshold is attributed primarily to the internal nanostructure of the thin film, which causes geometrical field enhancement inside as well as at the film/vacuum interface. Also, secondary effect of the presence of surface states, causing further field enhancement may not be ruled out. # 2003 Elsevier B.V. All rights reserved.